The invention relates to security seals of the kind which are applied to closed containers in such manner that the container may only be opened by breaking the seal, the condition of the seal thereby giving an indication of whether or not the container has been opened.
A common type of seal for this purpose comprises a main body element to which is secured one end of an elongate flexible element the opposite end of which may be inserted in a passage or aperture in the main body element. The passage or aperture and the flexible element are formed with cooperating formations which are designed to give non-return engagement of the end of the flexible element within the passage or aperture so that the seal may only be released by breaking or cutting the flexible element. In use of the seal the flexible element will normally be passed through registering apertures in two parts of a closure device or around the neck of a bag to be sealed, such as a money bag.
Known seals of this type are effective provided they are properly applied to the container and provided they have not been tampered with before being applied.
However, known seals of this type are susceptible to pre-tampering in such manner that although the seal may appear to be correctly closed it is in fact in such a condition that it may readily be released and then reconnected. For example, it may be possible, by inserting a tool into the aperture or passage in the body element, to deform, reshape or remove some or all of the formations before the flexible element is inserted, so that the flexible element may subsequently be withdrawn from the passage. Thus the seal may give the appearance of being correctly applied, but a person who carried out or is aware of the pre-tampering can subsequently open the seal to gain access to the contents of the container and then reclose the seal, applying adhesive to the interengaging parts of the flexible element and body element so that ultimate opening of the seal may again only be achieved by breaking it, giving the appearance that the seal has not been opened.
Alternatively, a thin blade or shim may be inserted into the passage in the body element, prior to insertion of the flexible element. The blade or shim then prevents interengagement between the formation on the flexible element and in the passage and thus permits subsequent withdrawal of the flexible element from the passage.
The present invention sets out to provide a form of security seal which is less susceptible to pre-tampering of this kind.